Monday, October 21, 2013

An ATmega countdown programmable timer

-- ref. 2012 --

This is an ATmega 8 based countdown programmable timer.

The timer alternates a "working" period, and a "pause" period. This is usefull if you have to run a device at a predetermined interval of days, for an amount of minutes you can chose.

It shows time using a double seven segment display.
User can select how much time to spend during the working and pause periods.

Periods can be selected from predefined values, stored in the hex firmware.
The pause period is expressed in days, the working in minutes.

There are five buttons:
  • pause +/- select the pause period
  • work +/- select the working period
  • start/stop iterate through perdiods
Both period are stored into internal avr eeprom, so that if the main power goes down, user settings are restored at next bootup.

The green led is on during the work period.

Setup parameters are contained in main.h

This library was developed on Eclipse, built with avr-gcc on Atmega8 @ 1MHz.


  • read risk disclaimer
  • excuse my bad english


  1. Hi. How to build hex file from c file? Please give me the software download link which can be converted.

    1. Hello, take a look at this tutorial, is a bit old but is still give you bases to make that work: